Impeller and cooling fan using the same

ABSTRACT

A cooling fan ( 10 ) includes a bottom housing ( 12 ), a top cover ( 14 ) covering the bottom housing, and impeller ( 16 ) and stator accommodated in a space formed between the bottom housing and the top cover. The impeller includes a hub ( 162 ), and a plurality of blades ( 164 ) radially and outwardly extending from the hub. Each of the blades includes a windward surface ( 164   a ) and a leeward surface ( 164   b ) which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.

BACKGROUND

1. Technical Field

The present invention relates to impellers and cooling fans using the same, and more particularly to an impeller which can generate more airflow with a low level of noise.

2. Description of Related Art

With continuing development of the electronic technology, electronic components such as CPUs generate more and more heat which is required to be dissipated immediately.

Conventionally, a cooling fan is used to produce an airflow which can remove heat from the electronic component. The cooling fan comprises a stator and an impeller being rotatable with respective to the stator. The impeller further comprises a hub and a plurality of blades radially and outwardly extending from the hub. In use, the blades of the impeller rotate around the stator to drive the airflow to flow towards the electronic component, thus cooling the electronic component continuously.

Increasing a revolving speed of the impeller relatively increases the amount of airflow, therefore a heat dissipation efficiency is relatively improved. However, increasing the revolving speed may correspondingly cause a rise of a noise level generated by the cooling fan, thus making a user near the fan feel uncomfortable.

What is needed, therefore, is an impeller which can overcome the above-mentioned disadvantage.

SUMMARY

The present invention, in one aspect, provides an impeller which generates more airflow without generating more noise. The impeller includes a hub, and a plurality of blades radially extending from the hub. Each of the blades includes a windward surface and a leeward surface which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.

The present invention, in another aspect, provides a cooling fan using the impeller. The cooling fan includes a bottom housing, a top cover covering the bottom housing, and impeller and stator accommodated in a space formed between the bottom housing and the top cover. The impeller includes a hub, and a plurality of blades radially extending from the hub. Each of the blades includes a windward surface and a leeward surface which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.

Other advantages and novel features of the present impeller and cooling fan will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, isometric view of a cooling fan according to a preferred embodiment of the present invention.

FIG. 2 is a top view of an impeller of the cooling fan of FIG. 1.

FIG. 3 is a top view of an impeller according to a second embodiment of the present invention.

FIG. 4 is a top view of an impeller according to a third embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made to the drawing figures to describe the preferred embodiment in detail.

Referring to FIG. 1, the cooling fan 10 includes a bottom housing 12, a top cover 14 covering the bottom housing 12, and an impeller 16 and a stator (not shown) accommodated in a space formed between the bottom housing 12 and the top cover 14.

The impeller 16 includes a hub 162 and a plurality of blades 164 radially and outwardly extending from the hub 162. An air channel 122 is formed between free ends of the blades 164 and an inner surface of a sidewall of the bottom housing 12 of the cooling fan 10. In operation of the cooling fan 10, the impeller 16 rotates in the bottom housing 12 along a counterclockwise direction and drives an airflow to flow towards an air outlet 124 of the cooling fan 10.

Referring to FIG. 2, each of the blades 164 includes a windward surface 164 a and a leeward surface 164 b which confronts the windward surface 164 a of a neighboring blade 164. The windward surface 164 a has a tip portion 1641 which is a forward curved surface. An extension direction of the tip portion 1641 of the windward surface 164 a confronts to the rotation direction of the impeller 16. The leeward surface 164 b has a tip portion 1642 which is a planar surface.

In the present impeller 16, the tip portions 1641, 1642 of the windward and leeward surfaces 164 a, 164 b of the blades 164 of the impeller 16 are respectively to be forward curved surfaces and planar surfaces. The present impeller 16 generates more airflow than an impeller whose windward and leeward surfaces have planar tip portions, and generates less noise than an impeller whose windward and leeward surfaces have forward curved tip portions. Therefore, the windward surfaces 164 a impel more air to flow towards the air outlet 124 of the impeller 16, and the leeward surfaces 164 b decrease noises generated during operation of the impeller 16. Thus, the present impeller 16 is optimized to generate more airflow without generating more noise.

Referring to FIG. 3, a second embodiment of the present impeller 26 is shown. In this embodiment, the tip portion 2641 of the windward surface 264 a of the blade 264 is a planar surface, and the tip portion 2642 of the leeward surface 264 b of the blade 264 is a backward curved surface. Planar surfaces can generate more airflow than backward curved surfaces and generate less noise than forward curved surfaces. Therefore, the present impeller 26 can generate more airflow than an impeller whose windward and leeward surfaces have backward curved tip portions, and generate less noise than an impeller whose windward and leeward surfaces have planar tip portions. The present impeller 26 is optimized to generate more airflow without generating more noise.

Referring to FIG. 4, a third embodiment of the present impeller 36 is shown. In this embodiment, the tip portion 3641 of the windward surface 364 a of the blade 364 is a forward curved surface, whilst the tip portion 3642 of the leeward surface 364 b of the blade 364 is a backward curved surface. Therefore, the present impeller 36 can generate more airflow than an impeller whose windward and leeward surfaces have backward curved tip portions or planar tip portions, and generate less noise than an impeller whose windward and leeward surfaces have forward curved tip portions. The present impeller 36 is optimized to generate more airflow without generating more noise.

In the hereinabove embodiments of the present impeller 16, 26, 36, the tip portions 1641, 2641, 3641 of the windward surfaces 164 a, 264 a, 364 a and the tip portions 1642, 2642, 3642 of the leeward surfaces 164 b, 264 b, 364 b of the blades 164, 264, 364 of the impeller 16, 26, 36 are different types of surfaces which have different capabilities in driving airflow and decreasing noise. Therefore, the present impeller 16, 26, 36 can be optimized to generate more airflow without generating more noise.

It is to be understood, how ever, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. An impeller comprising: a hub; and a plurality of blades radially extending from the hub, each of the blades comprising a windward surface and a leeward surface which has a different configuration from the windward surface, the windward surface having a tip portion selected from a group consisting of forward curved surface and planar surface, the leeward surface having a tip portion selected from a group consisting of planar surface and backward curved surface.
 2. The impeller of claim 1, wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a backward curved surface.
 3. The impeller of claim 1, wherein the tip portion of the windward surface is a planar surface, and the tip portion of the leeward surface is a backward curved surface.
 4. The impeller of claim 1, wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a planar surface.
 5. A cooling fan comprising: a bottom housing; a top cover covering the bottom housing; and impeller and stator accommodated in a space formed between the bottom housing and the top cover, the impeller comprising: a hub; and a plurality of blades radially extending from the hub, each of the blades comprising a windward surface and a leeward surface which has a different configuration from the windward surface, the windward surface having a tip portion selected from a group consisting of forward curved surface and planar surface, the leeward surface having a tip portion selected from a group consisting of planar surface and backward curved surface.
 6. The cooling fan of claim 1, wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a backward curved surface.
 7. The cooling fan of claim 1, wherein the tip portion of the windward surface is a planar surface, and the tip portion of the leeward surface is a backward curved surface.
 8. The cooling fan of claim 1, wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a planar surface. 